In a bicycle equipped with a prime mover, a bicycle running with a pedal drive, and an engine running with both the pedal drive and an engine power has been made. It is preferable to form the power system so that each running may be changed to be selected, and the running speed may be changed over to two steps of a low speed and high speed in the case of running with the engine power together. Therefore, if a generally adopted system with a sprocket and chain is to be applied entirely to such power system, the power transmitting system will become cumbersome and large. And, in case a mechanism for changing over the engine power is to be also provided in the power system, the structure will be complicated and the power transmitting system will necessarily become large.
Further, as a speed changing means and power change are required, with the above, the operating system will necessarily become two systems. The manual operating member will also become two systems and not only the structure will be complicated, but also the changing operation will be complicated and difficult. Particularly, when it is considered that prime mover-equipped bicycles are to be used also by females and children, and are therefore required to be able to be handled and operated as conveniently as bicycles, the above power system will not be desirable.
When making a speed change in the prime mover-equipped bicycle, i.e., from a low speed to a high speed or vice versa, even if a synchromesh gear type speed changing gear is adopted, instead of the sprocket-chain system in the power transmitting system, a neutral state will be generated in the power transmission at the time of the speed change, and a joint will be made in the speed changing operation.
Such generation of the neutral state by the speed changing means with gears is not desirable for the following reasons.
In a prime mover-equipped bicycle, when running with engine power is used simultaneously and the output of the engine is to be controlled by an artificial driving operation, if there is a neutral state in the change-over from a low speed drive running to a high speed drive running or vice versa, as the engine output is controlled by the artificial drive, the driving force will not be transmitted to the engine controlling means, the engine output will reduce at the time of the change-over, and the gear will be shifted in this state. Thus, the driving force will be transmitted to artificial driving means, such as pedals, and not only a smooth changing operation will not be achieved, but also the artificial operation will be dangerous.
In the prime mover-equipped bicycle, the engine is started by an artificial operation of driving the pedals. The changing means is operated with the bicycle running as it is, and the pedal driving system and engine starting system are connected with each other through clutch means to transmit the power of the pedals to the crankshaft of the engine to start it.
At the time of starting, as opposed to the bicycle running, besides this running drive, not only a large treading force to compress and move the piston through the crankshaft will be required, but also the clutch means connecting and disconnecting the pedal driving system and engine starting system with each other has not been considered. Problems such as the following will arise.
In the pedal starting device for the conventional prime mover-equipped bicycle, as the clutch means is connected independently of the position of the pedal, it may be connected with the engine starting system when the pedal is at or near the top dead point. Thus, even if a treading force is applied to the pedal, the pedal will be difficult to rotate.
At the time of starting the engine, all the load on the engine starting system will be applied to the pedal. Therefore, at or near the top dead point, the pedal will be difficult to rotate and the engine starting operation will be very difficult.
At the time of the bicycle running, it will be unnecessary to feed a fuel to the engine and to feed electricity to the ignition system or the like. Therefore, when the engine stops, it will be necessary to interrupt the fuel feed and to switch off the electric system. If this is not done properly, when the bicycle tumbles, though it is set at the bicycle running, the fuel may leak out of the float chamber of the carburetor or the like and will be dangerous. Also, if the electric system is left on, the battery will be discharged and depleted.
Therefore, a fuel cock and ignition switch are provided so that, when the engine is not being operated, i.e., at the time of the bicycle running, the fuel cock may be closed and the ignition siwtch may be off. However, in the prime mover-equipped bicycle, during the running, when the bicycle running is shifted to engine running or vice versa, the rider will find it troublesome to operate the separately provided fuel cock and ignition switch in response to the running condition, and will very likely carelessly forget the operation though the running condition is changed.
In the case of the shift from bicycle running to engine running, unless the above-mentioned cock and switch are operated, the engine will not start and therefore the rider will not fail to operate them. But, in the case of the shift from engine running to bicycle running, the rider will often forget to operate them. Unless the ignition switch is off, the engine will not stop and therefore the ignition switch will hardly be forgotten to be operated. But the fuel system will often be forgotten to be cut off. As a result, at the time of tumbling or the like of the bicycle, there will be a danger of fuel leaking out.